Patent GB-367393-A (GB)
Title: Improvements relating to the operation of barriers at railroad crossings and the like
IPC: B61L29/24
Filed: 1930-11-19
Abstract: 367,393. Operating crossing barriers. HADDAN, R., 31, Bedford Street, Strand, London.-(Belile, J. A.; Telegraph & Signal Department, Estacion Central, F. C. C. del U., Montevideo.) Nov. 19, 1930, No. 34824. [Class 65 (i).] In a level-crossing barrier of the lifting type operated by moving a weight carried on the barrier, the weight is arranged to move in an arc in the vertical plane of the barrier and is operated by an electric motor. In Fig. 3 the mechanism is carried entirely on the barrier, which is pivoted on an axle 7 ; the main part of the barrier extends to the right, and is attached to the mechanism casing shown by means of leaf springs. The balance weight comprises two heavy sectors 12 attached to the sides of a toothed wheel 10 on a spindle carried by the tail of the barrier. The wheel 10 is driven by gearing from an electric motor 17, and pins 21, 22 on either side of the wheel engage trip arms 19, 20 to operate a multiple switch 18 which reverses the circuits of the motor; the pins are so placed on the wheel that the weight is moved beyond the position it occupies when the barrier is in equilibrium at either end of its movement, so that a force is exerted tending to keep the barrier raised or lowered, but this force is insufficient to prevent the barrier from being raised by hand when necessary. The shaft 7 carries cranks connected to fluid check pistons 36, 37 which control the raising and lowering movements of the barrier respectively; the two ends of each cylinder are connected through two adjustable needle valves, the opening of one of which is covered when the piston approaches the inner end of the cylinder, so that the speed of the barrier is normally limited by both valves while it is checked at the end of the stroke by the smaller valve only. The barrier is controlled by a relay 68, Fig. 7, which when energized closes a circuit to certain contacts of the switch 18 for the motor to raise the barrier, and when de-energized closes the circuit to the other contacts of switch 18 for the lowering operation ; this relay may be controlled by treadles operated by passing trains. The initial motion of the weight in either direction does not move the barrier, but brings the weight to the position of equilibrium, and thereafter the barrier moves to remain in equilibrium with the weight ; after the barrier reaches its upper or lower stop, the motor continues to move the weight further, until the switch 18 is operated to reverse the connections. The barrier carries a switch 23, which closes a circuit to energize a relay 55 when the barrier is in its lowered position; the relay controls two lamps 61, 62 which indicate whether the barrier is lowered or raised. The contacts of the switches 23 of the several barriers at a crossing are connected in series, as shown in Fig. 7, so that the relay is only energized when all the barriers are fully lowered. The switch 23, shown in mid-stroke in Fig. 6, comprises a fixed contact 28 and a contact 27 carried by a tube 24, pivoted at its centre. The tube carries permanent bar magnets 41, under the poles of which are fixed pieces of soft iron 42, and a heavy ball 25 runs inside it. The tube is thus held by the magnets in either extreme position until the ball has moved considerably beyond the centre of the tube when the barrier tilts, and is then rapidly rocked over to the other position and held there.